Accession Number:

ADA048274

Title:

Drag, Flow Transition, and Laminar Separation on Nine Bodies of Revolution Having Different Forebody Shapes,

Descriptive Note:

Corporate Author:

DAVID W TAYLOR NAVAL SHIP RESEARCH AND DEVELOPMENT CENTER BETHESDA MD

Personal Author(s):

Report Date:

1977-12-01

Pagination or Media Count:

55.0

Abstract:

Resistance has been measured of nine bodies of revolution, having equal volume but varying forebody shapes. Forebody shapes ranged from extremely blunt to extremely fine and included two that were flat faced. The forebodies were altered by changing their length-to-diameter ratios lds and prismatic coefficients. Drag results indicate that when the prismatic coefficient is fixed and the LD is decreased, the residual resistance will increase modestly. Increasing the prismatic coefficient at small LDs increases residual resistance however, at moderate LDs it does not. The results suggest that a flat-faced shape in itself does not increase resistance. In addition to resistance experiments, transition regions on the models were located, using hot film probes. Calculations predicted laminar separation on five of the model forebodies. The hot film measurements confirmed that separation did occur at the locations predicted downstream of the separation locations, turbulent flow occurred immediately. The remaining four forebodies exhibited well-defined natural transition regions. Flow properties in the transition regions, measured by the hot film gages, have been compared with predicted spatial amplification ratios of disturbances, calculated by linear stability theory. Results have failed to show a single relationship between measured flow properties and computed spatial amplification ratios. Correlation of amplification factors with flow regimes varied, both with forebody shape and Reynolds number. Author

Descriptors:

Subject Categories:

  • Submarine Engineering
  • Fluid Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE


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